Topology Optimization and 3D Printing of Three-Branch Joints in Treelike Structures

Optimization and intelligent manufacturing are of particular interest and important to improve the severe situation of excessive mass and uneven stress distribution for three-branch joints in treelike structures. In this work, the optimal shape of the three-branch joints under vertical load is studied by topology optimization method, and the complex topology optimization joint is manufactured using three-dimensional (3D) printing technology because it is difficult to produce by conventional manufacturing processes. First, the original model is optimized by using the OptiStruct solver in HyperWorks version 14.0 (64-bit) software, and the element density cloud map and element isosurface map of the model are obtained. Then, the static behaviors of the topology optimization model are compared with those of the hollow spherical joint model which is commonly used in engineering and those of the bionic joint model based on empirical design. Finally, the 3D printing technology is used to produce the topology optimization joint model, the hollow spherical joint model, and the bionic joint model. The process of production is characterized by converting the finite-element file of topology optimization joint into a standard template library (STL) file and then reading it into the slicing software to generate the 3D printing commands. The results show that the topological optimization joint has the most balanced stress distribution and the best static behaviors, which can provide reference for the design of joints in treelike structures. It is effective and feasible to use the combined technology of topology optimization and 3D printing to design and manufacture three-branch joints.